In general, a wireless communication system has been widely developed to provide various types of communication services, such as voice and data.
The wireless communication system represents a multiple access system supporting communications with multiple users by sharing available system resources (bandwidth and transmission power).
For example, the multiple access system may include a code division multiple access (CDMA) system, a frequency division multiple access (FDMA) system, a time division multiple access (TDMA) system, an orthogonal frequency division multiple access (OFDMA) system, and a single carrier frequency division multiple access (SC-FDMA) system.
In addition, in order to improve the capacity of wireless communication by 1000 times with the aim of achieving 5G technology in 2020 in Korea, various technologies have been studied, for example, MIMO & Advanced Receiver, Smart Scheduler, eCoMP, Carrier Aggregation, New Bands, Advanced macros, HetNets Management, and Flexible small cells.
In particular, heterogeneous network technology (HetNets) having various cells exist within a close area is a technology for enhancing the capacity of the entire network by decreasing the size of cells and increasing the number of cells.
For example, HetNets is provided to enhance the capacity of the entire network by minimizing the size of cells and increasing the number of cells, and is known as the most effective technology capable of maximizing a data distribution effect (Off Loading) between terminals (user equipment) in a hot spot region by deploying a plurality of small cells within in a macro cell area.
The small cell represents a lower power base station, and is classified into a microcell, a picocell, and a femtocell depending on a transmission power and an installation location thereof, and even the simple deployment of small cells enables the capacity of the entire network to be increased. However, by enabling a terminal to use better uplink resources of the small cells through a cell range expansion (CRE) scheme, the network capacity is more increased without additional physical resources.
However, the above described CRE scheme may cause frequency interference of terminals located at an edge of a heterogeneous environment since the terminals use the same frequency in the heterogeneous environment.
In addition, the terminals located in an area expanded through the CRE scheme are subject to more serious interference by a macro cell that provides a better downlink signal.
Accordingly, such signal interference is the main factor of degrading the throughput of a terminal, and there is an urgent need to mitigate signal interference in 3GPP Rel-10, 11.